Process for removing sulfur compounds from gas

ABSTRACT

Sulfur compounds are removed from gases by contacting the gas with an aqueous suspension of a hydrolyzed admixture of an amphoteric component, more particularly oxide, hydrated oxide or hydroxide of aluminum, zinc, iron or manganese, and a basic component, more particularly an oxide or hydroxide of an alkali metal or alkaline earth metal.

United States Patent I i :91

Lowicki et a1.

[ 1 Sept. 25, 1973 PROCESS FOR REMOVING SULFUR COMPOUNDS FROM GASInventors: Norbert Lowicki,

Duisburg-Hamborn', Gernot Hanig, Dinslaken-Hisfeld, both of GermanyGrillo-Werke Aktiengesellschaft, Duisburg-Hamborn, Germany Filed: Dec.17, 1969 Appl. No.: 886,017

Assignee:

Foreign Application Priority Data Dec. 13, 1969 Germany P 19 62 586.5

Us. Cl. 423/225, 423/242 Int. Cl B0111 53/34 Field of Search 23/2, 250,178, 3;

Primary Examiner-Earl C. Thomas Att0rneyBurgess, Dinklage and SprungABSTRACT Sulfur compounds are removed from gases by contacting the gaswith an aqueous suspension of a hydrolyzed admixture of an amphotericcomponent, more particularly oxide, hydrated oxide or hydroxide ofaluminum, zinc, iron or manganese, and a basic component, moreparticularly an oxide or hydroxide of an alkali metal or alkaline earthmetal.

24 Claims, No Drawings PROCESS FOR REMOVING SULFUR COMPOUNDS FROM GASThis invention relates to a process for removingsulfur compounds fromgas containing at least one sulfur compound comprising contacting thegas with a hydrolyzed admixture of absorbent comprising (1) anamphoteric component and (2) a basic component, wherein amphotericcomponent (1) is at least one member of the group consisting of oxides,hydrated oxides and hydroxides of aluminum, zinc, iron, and manganese,and basic component (2) is at least one memher of the group consistingof oxides and hydroxides of alkali metals and alkaline earth metals.

U.S. Pat. application Ser. No. 525,996 filed February 8, 1966, nowpatent 3,492,083, discloses a process for the desulfurization ofindustrial waste gases, especially flue gases, which process comprisescontacting the gas with an absorbent comprising (1) an oxide, hydratedoxide or hydroxide of aluminum, zinc, iron or manganese or a mixture ofany two or more of such compounds, and (2) an oxide or hydroxide of analkali metal or an alkaline earth-metal or a mixture of any two ormoreof such compounds.

In a paper Das neue Abgas-Entschwefelungsverfahren der Grillo-Werke AGpublished in Zeitschrift fiir Erzbergbau und Metallhiittenwesen," Vol.XXI (1968), No. 12, pp. 567571, One of the inventors gives technicaldetails of the new method.

, The disclosure of the above-mentioned U.S. Pat. application Ser. No.525,996 and of the above-mentioned paper is included herein byreference.

British Pat. No. 1,144,071 which corresponds to the above-mentioned U.S.patent application discloses a process for the removal of sulfur andsulfur compounds from industrial waste gases, especially flue gases,wherein the gas containing sulfur compounds is contacted with a solidabsorbent which consists of a mixture of amphoteric components and basiccomponents. Oxides, oxide hydrates, and/or hydroxides of manganese and/or iron are especially mentioned as amphoteric components. The basiccomponent comprises oxides or hydroxides of alkaline earth metals and/oralkali metals, particular importance being attributable to magnesium.One absorbent described as particularly important in said British Patentis a mixture of the corresponding oxidic compounds of manganese and magnesium. If desired, this composition may additionally containcorresponding compounds of iron.

In the process of British Pat. No. 1,144,071, the waste gas to bedesulfurized is contacted with the absorbent in such a manner thatabsorbent compositions which are loaded with sulfur and sulfur compoundsare obtained. This loaded mass is then freed from sulfur in a separateprocess step by roasting. This desulfurization may be performed in aplurality of steps by first reducing the sulfur-loaded mass with carbon,especially coke, at temperatures above 1,000C. and then subjecting it ina second step to an oxidative treatment at a temperature within therange from 300 to 800C. However, in case of the commerciallyparticularly important mixtures of the oxidic compounds of magnesium andmanganese and, if desired, iron, it is also possible to subject theabsorbent which is loaded with sulfur and/or sulfur compounds directlyto oxidizing roasting in mixture with carbon without prior reducingtreatment. In this case temperatures of at least 750C. and preferablybetween 800C. and 1,000C. are used.

This regeneration by roasting involves the formation of oxide compoundsbetween the basic and the amphoteric metal components in the absorbentthereby mutually protecting both of the components against deactivationin the temperature range necessary for the roasting step. If compoundsof magnesium and manganese are used, well defined magnesium manganitesmay form.

To permit the re-use of the oxidic absorbent thus roasted as a highlyactive absorbent in the process of British Pat. No. 1,144,071, it isnecessary to hydrate the roasted composition. For this purpose, theroasted mass is slurried in water at a temperature ranging between 60and C. and treated for 2 to 8 hours.

The oxidic material obtainable by roasting is preferably composed ofwell defined mangesium manganites.

Detailed study of the dependence of absorption activity on the degree ofhydration of the absorbent has shown that, at least for the absorptionof S0 and l-l S, it is of decisive importance to approach as close aspossible the theoretically possible hydration. Both the rate of sulfurabsorption in the absorbent (and hence the residence time of the wastegas being purified in contact with the absorbent) and the time requiredfor substantially complete absorption of the particular sulfurcontainingcontaminant by the absorbent are unquestionably functions of the degreeof hydration. This is evident from the following comparative studies:

An absorbent comprising 3 moles of MgO and 1 mole of MnO, and,therefore, corresponding to the hypothetical formula Mg MnO istheoretically capable of absorbing 25.8% by weight of water. This wouldbe the maximum possible hydration on the assumption that all of the MgOis converted into Mg(Ol-l) and all of the MnO is converted into MnO(OHWhen designating the degree of hydration by the symbol a, it is equal to1 if the maximum possible water absorption for the analyticallydetermined molar ratio of the manganite present has taken place.

The study of the dependence of the degree of hydration a on hydrationtime and the temperature used is summarized hereafter in Table 1.

TABLE I Time in minutes a a a a a a a 0. l 0. 1 0. 1 0. 14 O. 17 0. 260. 30 0. 3'2 0. 48 0. 52 0. 58 0. 60 O. 64 0. 62 0. 56 0. 64 0. 73 0. 810. 85 0. 8'2. 0. 82 0. 58 0.70 0.70 0. 82 0.80 0.81 0. 82

In comparative studies, no dependence of the degree of hydration and ofthe rate of hydration on the molar ratio MgO/Mn0 within the range of 2:1to 6:1 and on the degree of intermixing of the solid mass and water wasfound provided that constant thorough intermixing of the suspension isassured. The production even of strong shearing forces by means ofturbine or tooth cage mixers had no influence.

The relationship between the degree of hydration and the activity of theabsorbent is apparent from the following studies:

50 Grams of the hydrated absorbent (based on dry substance in each case)are slurried in 100 ml of water. An air stream containing 1% $0 wasbubbled through the slurry while constantly stirring. The feed rate isone liter per minute and the temperature of the suspension is 70C. Theactivity of the mass is defined as the time in minutes elapsing beforefirst traces of SO break through.

How clearly the absorption activity depends on the degree of hydrationis evident from Table II:

Table [I :1 Period of 100% absorption in minutes 0.1 2 0.26 4 0.36 70.48 17 0.52 23 0.58 28 0.58 28 0.64 32 0.70 33 0.81 34 Furthermore,absorption experiments with dry or only slightly moistened and notpreviously hydrated absorbents showed no measurable SO absorption in thetemperature range between 20 and 90C. This was the case even when theair current containing SO had previously been saturated with steam.

In further experiments, appropriate absorbents were used to determinethe residence times which are neces- 35 sary to absorb about 90% of theS0 content from a So /air mixture containing 0.2% $0,. The absorbent wassprayed into the gas stream in the form of a suspension. The followingresults were obtained under otherwise entirely identical conditions withrespect to the gas, the temperature, rate and temperature of thecirculating suspension and the atomization pressure:

TABLE ill a Required residence time in seconds 0.1 19 0.45 2 0.64-0.700.05

This dependence on the degree of hydration of the absorbent determinedfor the absorption of S0 is correspondingly applicable to the absorptionof hydrogen sulfide from waste gases.

If a freshly roasted magnesium manganite is suspended in water and thesuspension is contacted with a gas containing hydrogen sulfide, noabsorption at all takes place irrespective of whether the gas isintroduced into the suspension or the latter is sprayed into the gas.

Studies have shown that absorption of H,S does not start to an extent ofpractical interest before the degree of hydration a is above 0.6. With avalues above 0.7, H,S is then absorbed rapidly, and with a values ofabout 0.8, absorption is substantially complete.

TABLE IV In these comparative tests, the following experimentalconditions were maintained: Rate of gas flow, 300 std. cu.m. per hours;H S content, 2 g. per std. cu.m.; gas temperature, 4548C.; residencetime, 1 second.

Based on this knowledge of the dependence of absorption activity ofabsorbent used on the degree of hydration, a process has now beendeveloped which relates to an improvement of the general processprinciple described in British Pat. 1,144,071. The new process isespecially directed to the greatest possible saving of expense in thedesulfurization of waste gas. Thus it gives consideration to the desiresof the industry involved, for which such desulfurization of waste gas isa mandatory but nevertheless only burdensome process step which does notcontribute to productivity of the plant.

Accordingly, it is an object of the invention to provide a continuousprocess for the absorption of sulfur compounds from waste gases intobasic absorbent compositions based on hydroxides and/or oxide hydratesof magnesium and manganese and, if desired, of iron with regeneration ofthe sulfur-loaded absorbent by reducing roasting followed by hydrationand with return of the hydrated metal oxide compounds thus formed intothe absorption stage. The new process comprises bringing the absorbentas an aqueous suspension in finely divided form into turbulent contactwith the waste gas stream in the absorption stage; recycling the aqueoussuspension into the absorption stage after separation from the treatedwaste gas stream while using temperatures up to about 1 10C. in theabsorption stage; separating absorbent from the aqueous suspension andpassing it to the regeneration stage while adding a corresponding amountof regenerated absorbent to the aqueous suspension.

Preferably the fresh absorbent is added to the circulating aqueoussuspension of the largely loaded absorbent at a rate sufficient that thepH value of the aqueous suspension of the absorbent ranges from about 6to 7 and preferably from about 6.5 to 7. According to a further featureof the invention, and this is one of the most important elements of thenew process, previous hydration of the regenerated mass is dispensedwith when returning the adsorbent regenerated by roasting into theaqueous suspension of the absorption stage. Instead, the magnesiummanganite compounds obtained by roasting and the corresponding ironcompounds which may be present are added as they are to the aqueoussuspension and are thus hydrated in situ in the absorption stage. Inthis manner, separate hydration of the absorbent, which has hithertobeen considered necessary, becomes superfluous. The overall process isthus greatly simplified for the user. Consideration must be given to thefact that, as a rule, regeneration of the sulfur-loaded absorbent is notperformed by the user of the waste gas purifying process but by a moreor less re mote sulfuric acid plant. The user of the desulfurizationprocess now needs only deliver the fouled absorbent separated from theabsorption stage to the plant performing the regeneration. in return hereceives regenerated, freshly roasted product which can be added as suchto the suspension in the absorption stage.

That such a simplification of the process is possible is due to thefortunate combination of a number of phenomena. On the one hand, theactivity of the absorbent has been found to be substantially independentof the degree to which it is loaded. As long as the absorbent is capableof absorbing sulfur compounds under the conditions of the process, itwill do so with the degree of activity derived mainly from its degree ofhydration. This means, however, that it is not necessary to operate withfresh suspensions of the absorbent or with suspensions which are onlyslightly loaded with sulfur and sulfur compounds to accomplishsatisfactory absorption results, but that it becomes possible to operatewith an absorbent which is almost completely loaded with sulfur andsulfur compounds. The remaining capacity in the absorbent suffices toobtain excellent desulfurization results as long there is the assurancethat the limit of absorptive capacity is not actually reached. Thesimplest method of detecting such a state of load or contamination is tomonitor the pH value of the aqueous suspension. When freshly regeneratedabsorbent is stirred into water and hydrated, a pH value ranging from8.5 to 9 establishes in the aqueous suspension that is formed. Theabsorbent, when completely loaded with sulfur and sulfur compounds,shows in aqueous suspension a pH which, as a rule, ranges around 6,especially just below 6. By controlling the pH of the suspension so asto keep it especially within the range of 6.5 to 7 by addition offreshly regenerated absorbent, the attainment of a very high level ofcharge is assured without reaching the limiting state of completeloading. This assures at the same time that the time for which absorbentis kept out of use between the absorption and regeneration cycles iskept to a minimum.

The fact that the return of the roasted absorbent into the aqueoussuspension of the absorption stage becomes possible without previousintensive hydration and that highly active suspensions are obtaineddespite the previously described dependence of activity of the mass onthe degree of hydration is due to the surprising discovery that the rateof hydration of the metal oxides involved is influenced in a decisivemanner by the pH of the aqueous medium. While two to eight hoursdepending on'temperature were previously necessary for the hydrationwith the use of pure water, it has now surprisingly been found that thishydration time is reduced to a few minutes when the dry, freshlyregenerated absorbent is added directly to the circulating suspensionwhich is precisely in the most favorable pH range between 6.5 and 7.

The performance of the absorption in the manner described herein,however, requires a reduction of the gas temperatures and humidificationof the gases to a higher degree than is called for in British Pat. No.1,144,071. Accordingly, wet desulfurization in a gas temperature rangebetween 40 and l 10C. and preferably between 70 and 100C is preferred.It is readily possible to desulfurize even cold gases, e.g., in atemperature range between 10 and 40C.

The very high activity of the highly hydrated masses now makes itpossible to operate with very brief periods of contact between theabsorbent suspension and the waste gas stream. As a rule, residencetimes of less than about 3 seconds are used, periods of less than 1second being substantially always sufficient for adequatedesulfurization of the waste gas stream, provided that sufficiently goodintermixing of gas and liquid is assured.

For this purpose, the suspension of the absorbent may be sprayed intothe waste gas stream, using conventional nozzles and pumps.

It has furthermore been found, however, that even nozzles andhigh-pressure pumps can be dispensed with if the suspension of theabsorbent and the waste gas stream are contacted under conditons suchthat the energy of the flow of the waste gas stream assures sufficientlyfine division and distribution of the suspension. ln this manner thereis no need for the expenditure of additional energy on the fine divisionof the suspension. Technically this is accomplished by passing the wastegas current through a reaction chamber having the form of a tube. If theflue gas stream in such a tube has a velocity of at least 5 m./sec andpreferably between 8 and 15 m./second, sufficient division anddistribution of the aqueous suspension will occur even when the latteris made to enter the gas stream through normal feed lines at thebeginning of the reaction tube. This reaction tube may especially be avertical tube to which the aqueous absorbent suspension is fed at thebase after the flue gas has been cooled and humidified by means of coldwater, if desired. The waste gas stream moving rapidly through the tubeentrains the absorbent suspension in finely divided or atomized form.After having left the reaction tube, the liquid phase is separated fromthe gaseous phase and returned to the base of the reaction tube.However, operation in the reaction tube may equally well be withcocurrent flow in downward direction. In this case, the suspension is tobe fed at the top of the reaction tube. Moreover, it is not absolutelynecessary to use a vertical reaction tube.

The surprisingly high activity of the absorbent composition and theresultant particularly great advantages for application in practice areobtained especially with magnesium manganites in which MgO and Mn(),,are present in molar ratios of l to 10 MgO combined with l to 4 MnOParticularly preferred are molar ratios of MgO/MnO ranging from 3:1 to6:1. lf iron is also present in the absorbent composition, its amountpreferably is not more than 50%, especially not more than 25% of themanganese proportion of an iron-free absorption composition consistingof manganese and magnesium compounds.

Another element of the invention which is important for the economy ofthe process relates to the separation of the loaded absorbentcomposition from the recycle stream of the absorbent suspension in theabsorption stage.

This portion of the suspension which is tapped from the recycle line maybe passed to a conventional drying operation, e.g., to a spray dryer orfluid bed dryer, where it is dried with a partial stream of the hot fluegas. The result is a sand-like, granular loaded absorbent mass which ispassed to the regeneration plant. This partial stream of hot flue gasused for drying is preferably introduced thereafter into thedesulfurization stage.

The recovery of a transportable, dry, loaded absorbent may, if desired,be substantially simplified by filtering the suspension prior totreatment with the hot flue gas and then subjecting to further dryingonly the filter cake constituted by the loaded suspension mass. For ithas surprisingly been found that the contents of dissolved sulfur in theaqueous phase of the recirculated suspension at pH 6.5 to 7 areextremely low. At a temperature between about 30 and 50C, the content ofdissolved sulfur in the liquid phase of the suspension is only about 30g./liter. This low sulfur content is apparently attributable to theformation of sparingly soluble sulfur-containing crystals under theprocess conditions, the nature of which has not yet been determined indetail. in any case, it is possible with utilizaiton of this phenomenonto filter the absorbent suspension withdrawn from the absorber, afterslight cooling if desired, and thus obtain a filter cake containing onlylimited amounts of water, e.g. 40 to 50% of water. This reduces not onlyconsiderably the amount of water to be removed by drying but alsopermits especially the use of the substantially cheaper belt dryers orplate dryers in place of the expensive spray dryers or fluid bed dryers.In addition, this procedure offers the advantageous possibility ofdrying the loaded composition directly in granulated form (pellets) forsubsequent regeneration in a fluidized bed. This facilitatestransportation and further processing. Furthermore, prior to drying orprior to shaping into pellets, as the case may be, the filter cake canbe mixed with coal dust which is preferably added in the amountnecessary for reduction of sulfate sulfur to 50,. It is also possible toimpregnate the pelletized, dried and loaded mass with waste oil prior toregeneration, thus bringing the reducing agent required for theregeneration of the absorbent into contact with the sulfur compounds.

For the regeneration, the information given in British Pat. No.1,144,071 is fundamentally applicable. Development in practice hasshown, however, that not only coal or coke can be used as reducingagent, but that other technical reducing agents are also suitable. Forexample, roasting of the loaded absorbent is possible in the presence ofcoal, coke, petroleum, natural gas or other reducing gases. Use ofelemental sulfur as reducing agent or at least as part thereof is alsopossible. The treatment may be performed in conventional roastingfurnaces of any type. Preferably, story roasting furnaces orfluidized-bed roasting furnaces equipped for waste heat economy areused. It may furthermore be preferred to use mixtures of carbonaceousreducing agents and sulfur. In this manner, normally concentratedroasting gases are obtained, which permit the roasting furnace capacityto be utilized to a conventional extent.

The following examples illustrate the invention.

EXAMPLE 1 A gas stream of 25,000 std.cu.m. per hour, at a temperature of220C, is introduced into a reactor in the form of a tube 6 meters longand 800 mm. in diameter. At the base of the vertical tube, thetemperature of the entering gas is reduced to about 95C. by sprayingwater into it. Just above are three tubes of 12 mm. inside diametereach, which are arranged one above the other at a distance of about 300to 400 mm. Through these tubes, an absorbent suspension of pH 6.5 ispumped into the reactor tube in cocurrent flow relation with the gaspassing through. The suspension is fed at a rate of 9,500 liters/hr. andthe concentration of absorbent therein is 30%.

The S0, content of the flue gas passed through the reactor tube ismeasured at the inlet end and at the outlet end. It is 2.4grams/std.cu.m. of S0, at the inlet and 0.165 grams/std.cu.m. at thetop, i.e., the outlet of the absorption section. Thus, the degree ofabsorption is 93%. The gas velocity in the tube is 15 m./sec.

By far the greatest part of the absorbent suspension entrained by thegas stream is separated by a centrifugal separator arranged downstreamof the absorption section while the slight residual amount is removed byfiltration through a layer of coarse coke.

The suspension flows back into a vessel provided with an agitator and isreturned into the reactor by the pump. A certain amount of suspension iscontinuously tapped from the return line and, in place thereof, freshregenerated absorption composition is metered directly into the stirredvessel by means of a vibratory proportioning trough, metering beingcontrolled by the pH value.

The loaded absorbent suspension tapped from the return line is fedthrough a second, smaller agitated tank to a spray dryer where it isdried with a partial stream of the hot flue gas.

The dry, loaded absorbent has a sandy-granular condition and isdelivered to the regeneration unit.

EXAMPLE 2 Flue gas containing 2.6 grams/std.cu.m. of S0 is desulfurizedat a rate of 25,300 std.cu.m./hr. by the method described in Example 1.

The absorbent suspension having a solids concentration of about 30% ismaintained at pH 6.5 to 6.8 by addition of fresh, dry and roastedabsorbent.

In the present case, 9,400 liters/hr. of suspension are recirculated.During the absorption process, this recirculating absorbent suspensionis warmed to a temperature of to C. A partial amount of about 530-550liters/hr. of the absorbent suspension running off from the absorptiontube and the drop separator arranged downstream thereof is tapped andpassed to a cooler. This tapped amount of suspension is cooled to atemperature of 2025C. thereby crystallizing the dissolved sulfates,sulfltes and, as the case may be, bisulfltes. A residual content ofthese compounds which reaches a substantially constant level andcorresponds to 28-30 g./liter of S remains in the aqueous phase.

To obtain a uniform crystalline mass the particle size of which is nottoo small, a quantity of liquid which is substantially greater than thatof the suspension being tapped continuously is initially charged and thewarm suspension is introduced into this liquid. In this manner, a largeamount of nuclei of crystallization is offered to the inflowing loadedabsorbent suspension and a well filterable crystalline mass is formed byuniformly stirring this stock suspension at a speed which is notexcessively high. Cooled suspension at a rate which is the same as thatof inflowing fresh suspension is continuously withdrawn from the stirredvessel and filtered. Continuously operating rotary filters themaintenance of which may be minimized may be used for this purpose.

The fllter cake contains about 30 to 35% of moisture and is passed to abelt dryer, plate dryer or a similar commercially available apparatus.

The dried filter cake contains about 15 to 19% S and, therefore, hasapproximately the same charge as the spray dried mass. The filtratehaving a residual content of about 28 to 30 g./liter of sulfur which ispresent substantially in the form of magnesium sulfate is returned tothe circulating absorbent suspension. At the same time, water is addedat a rate which corresponds to the amount of water removed in the formof residual mois- EXAMPLE 3 The filter cake consisting of the chargedabsorbent and obtained in the process described in'Example 2 is mixedwith fine coal sludge in an amount of 0.5 to 1 part of coal per part ofabsorbent (calculated as dry substance). The moist plastic mixture isthen scraped by feed rolls into the links of the chain belt of a beltdryer and dried. Due to shrinkage, the resultant hard and dry granuleshaving a size of, for example, 6 to 8 mm. can be readily poured from thebelt. The free flowing, non-dusting charged absorbent is very welltransportable. In addition, it has the advantage that these pellets lendthemselves particularly well to regeneration in fluidized-bed roastingfurnaces.

Of course, ground (or precipitated) elemental sulfur may be admixed tothe mass prior to drying in addition to coal to further improve thesubsequent roasting.

The Mno lMgO'molar ratio of the absorbent used in these exampleswas'l:3.5 to 1:4.2.

What is claimed is:

1. Process for removing a sulfur compound from gas containing at leastone sulfur compound comprising contacting the gas with an absorbent inaqueous suspension, said absorbent comprising hydrated, roastedadmixture of an .amphoteric component of the group manganese oxide,hydrated manganese oxide and manganese hydroxide, and a basic componentof the group magnesium oxide and magnesium hydroxide, the degree ofhydration, a, of the absorbent being at least 0.6, in a contacting zonefor charging of the absorbent with sulfur, withdrawing the absorbentfrom the contacting zone as an aqueous suspension, and recyclingwithdrawn aqueous suspension to the contacting zone.

2. Process according to claim 1, wherein the temperature of the gasduring said contacting is up to about 1 10C.

3. Process according to claim 1, wherein the temperature of the gasduring said contacting is about 40 110C.

4. Process according to claim 1, wherein the pH of the aqueoussuspension is about 6 to 7.

5. Process according to claim 1, wherein the pH of the aqueoussuspension is about 6.5 to 7.

6. Process according to claim 1, the suspension having a solids contentof about 50 wt.-%.

7. Process according to claim 1, the suspension having a solids contentof about 25 40 wt.-%

8. Process according to claim 1, the contacting time being less thanabout 3 seconds.

9. Process according to claim 1, wherein the gas is contacted with theaqueous suspension at a gas velocity of at least 5 meters/sec.

10. Process according to claim 1, wherein sulfur dioxide is removed fromthe gas.

11. Process according to claim 1, wherein hydrogen sulfide is removedfrom the gas.

12. Process according to claim 1, said admixture comprising magnesiummanganites.

13. Process according to claim 12, the magnesium manganites containingMgO and MnO in a molar ratio ofl to 10 MgO to l to 4 MnO 14. Processaccording to claim 13, said molar proportion of MgO to MnO ranging from3:1 to 6:1.

15. Process according to claim 1, wherein the temperature of saidcontacting is about -l00C.

16. Process according to claim 1, the contacting time being less thanabout 3 seconds, and the gas velocity during said contacting is at least5 meters/sec.

17. Process according to claim ii, the contacting time being less than 1second.

18. Process according to claim '1, and removing a portion of chargedabsorbent, and adding roasted absorbent to the recycled aqueoussuspension for hydration thereof in the aqueous suspension.

19. Process according to claim 18, and roasting the removed, chargedabsorbent and utilizing the roasted absorbent thereby produced as theroasted absorbent added to the recycle stream.

20. Process according to claim 18, wherein the pH of the aqueoussuspension is about 6 to 7.

21. Process according to claim 18, wherein aqueous medium of the aqueoussuspension is removed with the removed charged absorbent, the removedaqueous medium is filtered from the removed charged absorbent, and thefilter cake is dried, and the filtrate is returned to the aqueoussuspension.

22. Process according to claim 20, wherein said sulfur compound is atleast one of the group sulfur dioxide and hydrogen sulfide, thetemperature of said contacting is up to C, and said oxidic compoundscomprise magnesium manganites containing MgO and MnO, in a molar ratioof 1 to 10 MgO to l to 4 MnO 23. Process according to claim 22, whereinthe gas contacted with the absorbent is wet.

24. Process according to claim 22, and roasting the removed chargedabsorbent to produce the roasted absorbent added to the recycled aqueoussuspension.

W! 0* t ll NI

2. Process according to claim 1, wherein the temperature of the gasduring said contacting is up to about 110*C.
 3. Process according toclaim 1, wherein the temperature of the gas during said contacting isabout 40 - 110*C.
 4. Process according to claim 1, wherein the pH of theaqueous suspension is about 6 to
 7. 5. Process according to claim 1,wherein the pH of the aqueous suspension is about 6.5 to
 7. 6. Processaccording to claim 1, the suspension having a solids content of about15 - 50 wt.-%.
 7. Process according to claim 1, the suspension having asolids content of about 25 - 40 wt.-%
 8. Process according to claim 1,the contacting time being less than about 3 seconds.
 9. Processaccording to claim 1, wherein the gas is contacted with the aqueoussuspension at a gas velocity of at least 5 meters/sec.
 10. Processaccording to claim 1, wherein sulfur dioxide is removed from the gas.11. Process according to claim 1, wherein hydrogen sulfide is removedfrom the gas.
 12. Process according to claim 1, said admixturecomprising magnesium manganites.
 13. Process according to claim 12, themagnesium manganites containing MgO and MnO2 in a molar ratio of 1 to 10MgO to 1 to 4 MnO2.
 14. Process according to claim 13, said molarproportion of MgO to MnO2 ranging from 3:1 to 6:1.
 15. Process accordingto claim 1, wherein the temperature of said contacting is about70-100*C.
 16. Process according to claim 1, the contacting time beingless than about 3 seconds, and the gas velocity during said contactingis at least 5 meters/sec.
 17. Process according to claim 1, thecontacting time being less than 1 SECOND.
 18. Process according to claim1, and removing a portion of charged absorbent, and adding roastedabsorbent to the recycled aqueous suspension for hydration thereof inthe aqueous suspension.
 19. Process according to claim 18, and roastingthe removed, charged absorbent and utilizing the roasted absorbentthereby produced as the roasted absorbent added to the recycle stream.20. Process according to claim 18, wherein the pH of the aqueoussuspension is about 6 to
 7. 21. Process according to claim 18, whereinaqueous medium of the aqueous suspension is removed with the removedcharged absorbent, the removed aqueous medium is filtered from theremoved charged absorbent, and the filter cake is dried, and thefiltrate is returned to the aqueous suspension.
 22. Process according toclaim 20, wherein said sulfur compound is at least one of the groupsulfur dioxide and hydrogen sulfide, the temperature of said contactingis up to 110*C, and said oxidic compounds comprise magnesium manganitescontaining MgO and MnO2 in a molar ratio of 1 to 10 MgO to 1 to 4 MnO2.23. Process according to claim 22, wherein the gas contacted with theabsorbent is wet.
 24. Process according to claim 22, and roasting theremoved charged absorbent to produce the roasted absorbent added to therecycled aqueous suspension.